This invention relates to a collapsing device for an appliance to be implanted which belongs to a field of medical devices and, more particularly, for artificial blood vessels or the like and a method of using the collapsing device.
With the recent progress of medical technique, a technique enabling transvascular use of a variety of appliances such as artificial blood vessel without ventrotomy has reached a clinical stage. Specific examples of such a technique include a method of transferring and fixing an artificial blood vessel using a catheter which has been invented by the inventor of present claimed invention and disclosed in the paper A.(for example, PCT/JP96/01347 which has been published with International Publication No. WO96/36387). This method includes; inserting a catheter into a human body through an inguinal artery to position a front end thereof near an affected portion in which an aneurysm or the like is present, inserting a tubular artificial blood vessel provided with collapsible/restorable elasticity into the catheter in a collapsed condition, transporting the artificial blood vessel to a predetermined location near the affected portion by the use of a transporting device or a hauling device, and releasing the artificial blood vessel from the catheter at the location, thereby to position the artificial blood vessel in an affected blood vessel having the aneurysm.
In the above-described document a collapsing device for keeping the artificial blood vessel in a collapsed condition during transportation works as follows; the artificial blood vessel is bound by a string at given portions of an outer circumference thereof, a retaining rod is passed into the string to keep the artificial blood vessel in a collapsed condition so as to release the collapsed condition from a remote place, the artificial blood vessel is transported to a target position and subsequently the retaining rod is drawn out of the string to release the string so as to restore the artificial blood vessel.
However, in order to make it possible to transport the artificial blood vessel smoothly, it is preferable to collapse the artificial blood vessel in a more appropriate condition. For example, in the artificial blood vessel described in the above document collapsible/restorable ring members are arranged intermittently along an axial direction. Due to this arrangement of the ring member, a protuberance is made locally on an outer face of the artificial blood vessel when the artificial blood vessel is collapsed by means of a string. Consequently, a dragging resistance will be generated while transporting the artificial blood vessel in a catheter. As a result, in order to reduce the dragging resistance, it is more preferable to make protuberances generate as least as possible on the outer face of the collapsed artificial blood vessel.
In order to solve the above problems a collapsing device for an appliance in accordance with the invention comprises a wrapping member which is generally flat when spread and a retaining member which holds the wrapping member in a condition of being rolled in order to keep a collapsible/restorable elastic appliance in a collapsed condition, to transport the appliance to a target position and subsequently to restore the appliance into a predetermined shape by releasing it from the collapsed condition, and is characterized by that the appliance is contained inside the wrapping member which is held by the retaining member in a collapsed condition and then the retaining member is separated from the wrapping member at the target position to spread the wrapping member so as to release the appliance.
It is effective if the wrapping member is made of an expansible material. For further improve a stretching properties it is effective if the wrapping member is in a shape of a mesh, and especially it is preferable that the mesh is woven with wefts and warps or the wrapping member is made of polyurethane fibers.
As a concrete embodiment to facilitate holding or spreading the wrapping member, it is represented that the retaining member is a wire rod which sews overwrapped edges of the wrapping member. As a concrete example of the wire rod it is preferable to use a wire made of nickel titanium. The wire rod may be a string which sews the overwrapped edges of the wrapping member and so arranged that a retaining member is passed through a loop formed at an end portion of the string.
As a preferable example to which the present claimed invention is applied it is represented that the appliance is in a shape of a tube and so arranged as to be contained inside the wrapping member held by the retaining member in a collapsed condition. Among the above, it can be a more preferable example to which the present claimed invention is applied that the appliance is so arranged that intermittently arranged ring members are bridged by a flexible cover and each of the ring members is collapsed into a wavy shape having a peak and a valley alternately and repeatedly along a circumferential direction thereof.
As another preferable example to which the present claimed invention is applied, it is represented that the appliance comprises a tubular body portion and a tubular branch portion which branches from a part of the tubular body portion with its internal space communicating with the body portion and so arranged that the body portion of the appliance is contained in a first wrapping member held by a first retaining member in a collapsed condition and the branch portion is contained in a second wrapping member held by a second retaining member in a collapsed condition. Among the above, it can be a more preferable example that the appliance is so arranged that the body portion is so made that intermittently arranged ring members are bridged by a flexible cover and the branch portion is so made that intermittently arranged ring members are bridged by a flexible cover with its internal space communicating with a part of the body portion, wherein the body portion and the branch portion of the appliance are so arranged that each of the ring members is folded into a wavy shape having a peak and a valley alternately and repeatedly along a circumferential direction thereof.
As a simple method of using the collapsing device in accordance with the present claimed invention, it is preferable that the wrapping member is mounted on near an end portion of an outer circumference of a pipe member, the appliance is inserted into inside of the pipe member at a position corresponding to the position where the wrapping member is mounted and the wrapping member and the appliance are simultaneously drawn out of the pipe member in a condition that both of the wrapping member and the appliance are restrained from moving interactively at the end portion so as to contain the appliance inside of the wrapping member.
If the appliance has a branch, the following step is preferable; the first wrapping member is mounted on near an end portion of an outer circumference of a pipe member, the body portion and the branch portion of the appliance are inserted together into inside of the pipe member at a position corresponding to the position where the first wrapping member is mounted, the first wrapping member and the body portion are drawn simultaneously out of the pipe member in a condition that both of the first wrapping member and the body portion are restrained from moving interactively at the end portion so as to contain the body portion and the branch portion of the appliance together inside of the first wrapping member, subsequently a part of the first wrapping member is released from a condition of being held by the first retaining member, the branch portion is drawn out through the part of the first wrapping member, then the second wrapping member is mounted on near an end portion of an outer circumference of a pipe member, the branch portion is inserted into inside of the pipe member at a position corresponding to the position where the second wrapping member is mounted and the second wrapping member and the branch portion are drawn simultaneously out of the pipe member in a condition that both of the second wrapping member and the branch portion are restrained from moving interactively at the end portion so as to contain the branch portion inside of the second wrapping member.
In order to make it easier to mount the wrapping member it is preferable that the wrapping member is made to open wider gradually along a tapered guide portion and then to be mounted on an outer circumference of the pipe member arranged at a position continuous to the guide portion. It is preferable that the guide portion is applied with a material of cutting frictional resistance such as silicon or the like.
As a procedure after transporting the collapsing device in accordance with the present claimed invention the following procedure is effective; the appliance is transported to a target position, the appliance is restored into a predetermined shape by releasing the wrapping member from a condition of being held by the retaining member and then the retaining member is removed from the target position with the wrapping member left at the position together with the appliance.
In accordance with the collapsing device of the invention, since whole of the appliance is contained inside of the tubular wrapping member, it is possible to reduce a protuberance which is generated locally on an outer face of the appliance compared with a case in which the appliance is bound with a string partially to keep a collapsed condition. In addition, if the appliance is released from a condition of being held by the retaining member at a target position, the wrapping member is spread and a space surrounding the collapsed appliance will be open wide. As a result, interference with a movement of restoring the appliance into a predetermined shape can effectively be avoided.
In this case, if the wrapping member is made of an expansible material, the material of the wrapping member stretches so as to wrap the appliance effectively when the wrapping member is held to wrap the appliance whereas the material of the wrapping member shrinks so as to be quickly separated from the appliance and move to a certain position near the target position when the wrapping member is released from a condition of being held.
In case the material of the wrapping member is in a shape of a mesh, a stretching properties can effectively be demonstrated because a cross of the mesh stretches or shrinks.
If the mesh is woven with wefts and warps, a stretching properties can sufficiently be demonstrated along both of lengthwise and crosswise and a cross of the mesh is hard to be moved as well as hard to be loosened, thereby to produce the above-mentioned effects for certain.
If the material of the wrapping member is made of polyurethane fibers, it is easy to provide the material with a stretching properties, in addition, the wrapping material can be left at a target portion in a body together with the appliance after released because polyurethane fibers are not harmless to a human body.
If the retaining member is a wire rod and overwrapped edges of the wrapping member are sewed by the wire rod, it is possible not only to keep the wrapping member in a shape of a tube but also to release the wrapping member directly from a condition of being held with relatively little resistance by pulling the wire rod lengthwise.
If the wire rod is made of a wire of nickel titanium, it is possible to obtain an extremely flexible elasticity, thereby to be convenient for transporting the appliance. In addition, a length of the wrapping member can be adjusted depending on a demand since it is possible to cut only the wrapping member along a direction at right angles generally to the wire in a condition of passing the wire therethrough without cutting the wire, if necessary. Further, if the above-mentioned wire is used, there is no fear of getting entangled like a thread.
With an arrangement in which the retaining member is a string which sews edges of the wrapping member and a retaining rod is passed through a loop formed at an end portion of the string, it is possible not only to hold the wrapping member in a shape of a tube but also to release the wrapping member from a condition of being held indirectly if the string is released from restraint of moving by hauling the retaining member so as to draw the retaining member out of the loop. If a string having elasticity is used, it is easy to release the string out of the loop, thereby to be especially effective.
In accordance with the invention, it is extremely effective in collapsing a tubular appliance like an artificial blood vessel which becomes bulky when restored into a predetermined shape. More specifically, if the appliance is so arranged that ring members arranged intermittently are bridged by a flexible cover and each of the ring members is collapsed into a wavy shape having a peak and a valley alternately and repeatedly along a circumferential direction thereof, it is likely to happen that protuberance is made locally on the outer face of the appliance due to collapsed ring members. However, since whole of the appliance in accordance with the invention is wrapped by the wrapping member including protuberance, it is possible to firmly press down protuberance, thereby to form a smooth curved surface on the outer face thereof.
In addition, in accordance with the invention, for a branched appliance wherein a tubular branched portion branches from a tubular body portion it is possible to collapse the branched appliance like an appliance in a tubular shape as a whole by applying a wrapping member and a retaining member to each of the body portion and the branch portion respectively. In case each of the body portion and the branch portion is so made that intermittently arranged ring members are bridged by a cover, it is possible to firmly press down protuberance generated on the body portion or the branch portion, thereby to form a smooth curved surface, on the outer face of the body portion and the branch portion respectively.
Since the method of using the collapsing device of the invention comprises steps of mounting the wrapping member on near an end portion of an outer circumference of a pipe member, inserting the appliance into inside of the pipe member and drawing the wrapping member and the appliance simultaneously out of the pipe member in a condition that both of the wrapping member and the appliance are restrained from moving interactively at the end portion, it is possible to contain the appliance inside of the wrapping member in an appropriate collapsed condition through simple procedures, even though the wrapping member is highly elastic and the appliance is highly elastically restorable.
For a branched appliance, if a procedure comprises steps of collapsing the body portion by the use of the first wrapping member and the first retaining member, releasing a part of the first wrapping member from a condition of being held by the first retaining member, drawing the branch portion out of the first wrapping member through the part and collapsing the branch portion by the use of the second wrapping member and second retaining member, it is possible to keep the body portion and the branch portion in an appropriate collapsed condition respectively without causing a big inconvenience in spite of the branched appliance.
If the wrapping member is mounted on an outer circumference of the pipe member along a tapered guide portion to open wider gradually, it is possible to move the wrapping member to the outer circumference of the pipe member so as to be mounted thereon with ease and securely even if a shrinkage degree of the wrapping member is so high that the wrapping member shrinks quite a lot.
If the appliance is transported to a target position, and restored into a predetermined shape by releasing the wrapping member from a condition of being held by the retaining member and subsequently only the retaining member is released from the target position with the wrapping member left at the position together, it is not necessary to remove the wrapping member, thereby to simplify a procedure of transporting the appliance.